Key Techniques Of The Next Generation Green TWDM-PON

The increasingly serious energy and environment issues have been getting more and more attentions, which results in lots of hot discussions concerning the areas of ecology, economy, politics and society. With the dramatically growing number of network users and the rapid development of network technologies, the energy consumption of networks is increasing at an annual rate up to 15%~20%. It is imperative to improve the energy efficiency of network and reduce the energy consumption from the perspectives of the governments, network operators and end users. As a key part of communication networks, the access network has huge number of equipments and its energy consumption dominates the total power consumption of whole communication networks.Passive optical network(PON) technology has been well developed and large-scale deployed, which firmly established PONs as an essential part of the high-speed access networks. The TWDM-PON(Time and Wavelength Division Multiplexed PON) reuses the current TDM-PON(Time Division Multiplexed PON) and WDM-PON(Wavelength Division Multiplexed PON) technologies in a stack way. It increases the system capacity significantly by leveraging the WDM technologies. Mostly important, the TWDM-PON can coexist with current deployed PON systems due to its backward compatibility. ITU(International Telecommunication Union) and FSAN(Full Service Access Network) have started developing the TWDM-PON standards since the year 2012. TWDM-PON is dominated as the best technical candidate among NG-PON2(Next Generation PON 2) technologies, and it is selected by FSAN as the recommended solution for NG-PON2.This thesis concentrates on improving the energy efficiency, and optimizing the deployment of components, to green the TWDM-PON systems. Three novel energy-saving mechanisms have been proposed and discussed: ONU migration, wavelength relocation and dynamic ONU working group. The main contents and the key contributions of this thesis are presented as follows:1. ONU Migration in TWDM-PON systemWe propose a novel ONU migration mechanism within the TWDM-PON framework. By introducing the ONU migration mechanism, the working ONUs can be migrated from one wavelength to another according to the real-time network traffic.1)With ONU migration in the TWDM-PON systems, the working ONUs can be rearranged to a minimum number of wavelengths and the rest of wavelengths can thus be turned off to save the power.2)ONU migration is easy to implement, the key messages and commands defined in current PON standards can reused in the migration procedures.3)It is flexible for the network operators to configure different migration parameters, e.g. migration internal, based on the different user SLA(Service Level Agreement) requirements.2. Wavelength relocation in TWDM multiple PON systemThe Multiple PON system utilizes some wavelength routing devices, e.g. AWGR, to integrate multiple PON systems with one OLT. The proposed TWDM multiple PON architecture encapsulates scalability and interoperability of different TWDM-PON systems. We propose a novel wavelength relocation mechanism to green the TWDM multiple PON systems.1)With wavelength relocation, the pools of wavelengths and transceivers can be shared across all the connected TWDM-PON systems. Some of the deployed wavelengths and transceivers can thus be powered off to save power when the traffic is not at peak time.2)Besides improving the energy efficiency of the TWDM multiple PON system, wavelength relocation can contribute to saving the capital deployment cost, as the wavelengths and associated transceivers can be shared among these PON systems, and they are not required to be deployed at full swing.3)It is easy to implement the wavelength relocation, the key messages and commands defined in current PON standards can reused in the wavelength relocation procedures.3. Dynamic ONU working group in TWDM-PON systemDynamic ONU power-saving working group is proposed to improve the energy efficiency of ONU in TWDM-PON system. ONUs with similar traffic categories are grouped and migrated to some of the wavelengths. According to its actual traffic categories, each group can implement a most suitable power saving technique.1. ONUs can be grouped and migrated to different wavelengths and implement the most suitable power saving mechanism according their actual traffic categories2. The flexibility in defining the exit and entry criteria of the dynamic power-saving ONU working group can overcome the difficulty in handling the network traffic fluctuation.